I'm a homebirth midwife, and I don't agree that weight alone should be
a contra-indication to a homebirth. The only good reason I can think of
is that there might be a time when the birth attendants might need to help
the mom change positions, and moving a larger woman will require more strength
on the part of the birth attendants. This was a serious consideration in
the days when homebirth midwives were scarce and often worked completely
alone. Then, it was common for just the midwife and the birthing woman's
partner to be the only adults present. These days, in our area anyway,
most midwives bring a second midwife and sometimes an apprentice or labor
coach. Together with the woman's family, this should be enough muscle to
move any woman.

The subject has come up several times on the midwife list, and the consensus
among both homebirth and hospital midwives is that size has little to do
with giving birth. In particular, there are homebirth midwives who serve
Amish communities, where many of the women are large. These midwives say
they haven't noticed any particular problems due to size.

Let's take a look at what _Williams Obstetrics_ says about it.

First, it admits that there's no standardized definition of obesity,
so investigators have used a variety of classifications, generally based
on weight alone, ignoring muscle mass or strength.

Here's a list of their "complications due to obesity", with my comments.
And, for the record, their definition of obesity is > 250, and this is
compared with women weighing < 200. It sounds as if there isn't a lot
of clear evidence regarding the 200-250 pound zone.

Complications during pregnancy are limited to diabetes and hypertension.
Well, these alone could be contra-indications to homebirth. If they're
not there, they're not there, regardless of the woman's size. If the woman
is healthy at 39 weeks, it seems unlikely that she will develop these complications
simply because she gives birth at home.

Another "complication" is a postterm pregnancy. Well, personally, it
makes sense to me that women with slower metabolisms are going to grow
babies more slowly. This is only a complication in the medico-legal sense.
Biophysical profiles can be done to assess postterm fetal well-being, regardless
of maternal size.

The remaining "complications" are pitocin induction and augmentation.
Well, the increased induction obviously comes from the increased rate of
postterm babies, and from the medico-legal fear that "the baby will be
big".

In fact, "macrosomic infants" are another one of the complications,
meaning that large women have large babies. The only substantive related
"complication" is shoulder dystocia. Listing this as a complication is
completely specious, as all OBs agree that there is no way prenatally to
predict shoulder dystocia. There are only ways to predict that you will
lose a lawsuit if there's a problem. (And, by the way, most reported incidents
of "shoulder dystocia" are really tight shoulders, which one might expect
to see in a woman with a well-padded pelvis. This is very different from
a case of real shoulder dystocia, which is only about bone, i.e. the baby's
shoulder bone becoming impacted behind the mother's pubic bone.)

Despite their alleged scientific approach, no evidence is presented
that the size of a healthy woman has any bearing on outcome. No distinction
is made between large, healthy women and large women with diabetes and
hypertension. If there is an increased rate of diabetes and hypertension
in larger women, then, yes, the overall statistics will reflect the increased
rate of "complications" that one would expect from diabetes and hypertension.

Personally, I think weight restrictions alone are an extension of our
cultural prejudice against women who don't conform to expectations that
they should remain as small as possible.

Ah, here they start to look at the difference between healthy circumstances
and pathological circumstances, rather than making blanket statements that
underweight women have increased rates of complications. They point out
that it's important to understand the many causes, and that about 75 percent
of small-for-gestation-age infants are constitutionally small. "Small women
typically have smaller babies. . . . In a small woman with a small pelvis,
the birth of a small baby whose genetically determined weight is below
the average for the entire population is not necessarily an undesirable
event."

One could make analogous statements about large women and large babies,
but they don't.

Oddly enough, this is the section where they start to make some sense
about large women. "If the mother is large and otherwise healthy, however,
below-average maternal weight gain without maternal disease is unlikely
to be associated with appreciable fetal growth retardation. Marked restriction
of weight gain during pregnancy should not be encouraged."

So, they're a little inconsistent.

If anyone tells you that size is a problem in a healthy woman giving
birth, ask for some real studies, not just prejudice.